Raman spectroscopy is a non-invasive method to predict the total viable microbial count through the packaging material of vacuum packaged lamb meat

This study investigated the use Raman spectroscopy to predict the in-pack total viable count (TVC) of microorganism on vacuum packaged and chilled lamb meat. A total of 159 lamb longissimus lumborum muscles (LL) were sourced from an investigation into the effects of chilled storage periods and packaging types. Each LL was measured while still in its packaging using a hand-held Raman spectroscopy device (785 Mira, Metrohm®, Melbourne, AUS) using a 785 ± 0.5 nm laser, 8–10 cm⁻¹ spectral resolution. After Raman measurements, the samples LL were removed from their packaging and analysed for TVC. It was found that Raman spectra only provided modest predictions (R² = 0.29; RMSE = 1.34) of in-pack TVC. Raman spectra could, however, differentiate between lamb meat with high and low TVC (based on log 5 CFU/g) with relatively high accuracy (92.5 %) and sensitivity (88.0 %). These findings confirm the application of Raman spectroscopy to provide non-destructive information of the in-pack status of TVC for chilled lamb meat.